Interfacial Engineering of NiO/NiCo₂O₄ Porous Nanofibers as Efficient Bifunctional Catalysts for Rechargeable Zinc–Air Batteries

Abstract

To meet the crucial demand of regenerative Zn–air (ZA) batteries, low cost, highly efficient, and durable electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are needed to replace the noble metal. Herein, porous NiO/NiCo2O4 nanofibers with superior electrocatalytic performance are synthesized by a facile electrospinning strategy with precursor transition metal salts in nonstoichiometric ratio, which confers the heterostructured NiO/NiCo2O4 with abundant interface-related active sites and electronic transmission channels. Density functional calculation results reveal the chemical bonds easily form between NiO and NiCo2O4 to facilitate the charge transfer, while X-ray absorption fine spectroscopy and X-ray photoelectron spectroscopy results demonstrate there are abundant Ni3+ and Co3+ species in NiO/NiCo2O4 due to the interfacial engineering. As a result, the NiO/NiCo2O4 porous nanofibers exhibit highly efficient and durable performances of OER and ORR in KOH solution, including a lower overpotential of 357 mV at 10 mA cm–2 (OER) and half-wave potential of 0.73 V (ORR) than that of the individual. What’s more, the NiO/NiCo2O4-based ZA battery displays excellent specific capacities of 814.4 mA h g–1, and good cycling stability of 175 h. Additionally, the flexible ZA battery displays a long cycling life of 14 h and decent flexibility. This work shows that construction of the heterostructure could provide a feasible method to optimize their electrocatalytic performance and make them widely used in power source devices.

Recent Advances on Electrospun Nanomaterials for Zinc–Air Batteries

“…Meanwhile, metal oxide has a better affinity binding effect for oxygen, which can exhibit the character of excellent stability under alkaline or acidic conditions, and further contribute a synergetic effect with the carbon electrospun nanofibers. [ 111–121 ] Recently, the Co 3 O 4 hollow particles (Co 3 O 4− x HoNPs) supported on hierarchically porous N‐doped carbon structure (HPNCS) are prepared by the growth of leaf‐like Co‐ZIFs and subsequent heating treatment of electrospun nanofibers ( Figure a). [ 122 ] The carbon flake structure can be distributed on carbon nanofibers, which have a large surface area and rich oxygen vacancy defects (Figure 10b).…”

Electrospinning of BCNNTs/PVA/PEDOT composite nanofibers films for research thermoelectric performance

“…Zhan et al synthesized NiO/NiCo 2 O 4 heterogeneous fiber structure electrocatalyst with good coupling interface by electrospinning. 11 Further, the nonwoven polymer fiber materials prepared by electrospinning have been applied in practice. For example, they are beneficial to utilize as a gas mask to protect people's respiratory system, and can also be used in the air purification system of the operating room.…”

Heterostructure and Oxygen Vacancies Promote NiFe2O4/Ni3S4 toward Oxygen Evolution Reaction and Zn‐Air Batteries

“…[18] Gao and Xue groups fabricated the NiO/NiCo 2 O 4 porous nanofibers, and such nanofibers exhibited efficient and durable OER performance. [19] In recent study, Zheng et al prepared an NiSe 2 / CoSe 2 heterostructure with dense interfaces, which showed incredible OER activity, manifested by an extremely low overpotential of 286 mV at 10 mA cm À 2 in 1 M KOH. [20] Heteroatom doping, [21] defect engineering, [22] single atom/active site construction, [23] and other strategies have been employed as available means to optimize the electrocatalytic performance.…”

“…discovered that, graphitic carbon nitride/carbon nanotubes supported NiCo 2 S 4 showed superior OER performance to the benchmark RuO 2 catalyst, featuring low overpotential, high efficiency and robust stability [18] . Gao and Xue groups fabricated the NiO/NiCo 2 O 4 porous nanofibers, and such nanofibers exhibited efficient and durable OER performance [19] . In recent study, Zheng et al.…”